1. Field of the Invention
The present invention relates to a method of evaluating stress by utilizing the concentration of amino acids in blood (plasma), as well as a stress-evaluating apparatus, a stress-evaluating method, a stress-evaluating system, a stress-evaluating program and a recording medium.
2. Description of the Related Art
It is known that when physical and mental adaptation to environmental changes, human relations and fatigue is difficult, stress is caused and there occur various symptoms such as imbalanced lifestyle habit and eating disorder. Such symptoms are estimated as the origin of lifestyle-related diseases such as obesity, hypertension, hyperlipidemia and diabetes mellitus, and how stress is early noticed and coped with is an important task for preventing lifestyle-related diseases.
In diagnosis (stress finding) of mental disorders caused by stress, an interview sheet is widely used and includes ICD-10 (International Classification of Diseases, 10th edition) prepared by World Health Organization (WHO) and DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) prepared by American Psychiatric Association (APA).
The method of objectively measuring stress includes an electrophysiological method of measuring brain waves and heart rates (see Japanese Patent No. 3070346) and biochemical methods of measuring stress protein (see Japanese Patent No. 3429043 and Japanese Patent No. 3445038) and expression of various genes (see JP-A-2003-274949, JP-A-2004-208547, JP-A-2005-143420, JP-A-2005-312435 and JP-A-2006-15).
In addition, it is known that resistance to stress is enhanced when amino acids are ingested (see WO2005/07408), and that the concentrations of amino acids in blood vary under stress.
In plasma from patients with major depressive illness, Altamura C et al. (see “Altamura C, Maes M, Dai J, Meltzer H Y (1995) Eur Neuropsychopharmacol.5. Suppl 71-5.”) show that the concentrations of taurine, serine/glycine are increased and the concentration of glycine is decreased; Mitani H et al. (see “Mitani H, Shirayama Y, Yamada T, Maeda K, Ashby C R Jr, Kawahara R (2006) Prog Neuropsychopharmacol Biol Psychiatry. 30(6). 1155-8.”) show that the concentrations of taurine, glycine, glutamine and glutaric acid are increased; Mauri M C et al. (see “Mauri M C, Ferrara A, Boscati L, Bravin S, Zamberlan F, Alecci M, Invernizzi G (1998) Neuropsychobiology. 37(3).124-9.” and “Mauri M C, Boscati L, Volonteri L S, Scalvini M E, Steinhilber C P, Laini V, Zamberlan F (2001) Neuropsychobiology. 44(3).134-8.”) show the concentrations of lysine, taurine, glutamic acid, tyrosine/LNAAs (the sum total of valine, leucine, isoleucine, tyrosine and phenylalanine) are increased and the concentration of tryptophan/LNAAs is decreased; and Kishimoto (see “Eiji Kishimoto (1993), Medicine of Brain and Sprit, Vol. 4, No. 2, April, 1993”) shows that the concentrations of tryptophan, tyrosine, lysine, leucine, isoleucine, phenylalanine, methionine, alanine, glutamic acid, arginine and histidine are decreased.
In addition, Altamura C et al. (see Nonpatent Literature 1) show that major depressive illness can be discriminated by a linear discriminant using glycine, glutamic acid and taurine, and Mauri M C et al. (Nonpatent Literatures 3 and 4) show that tyrosine/LNAAs, tryptophan/LNAAs, can serve as indicators of the pharmaceutical effect of an antidepressant.
However, the results in the interview sheet used in finding and diagnosis of stress are often subject to a subject's subjectivity, which causes a problem of reduced accuracy in the results in the interview sheet.
For extracting stress evidence by highly accurate diagnosis, an index capable of objectively diagnosing stress without a subject's subjectivity has been desired. However, in the methods of measuring brain waves and heart rates, stress protein or expression of various genes among the methods of objectively diagnosing stress as described above, there is a problem that measurement of the diagnostic index and interpretation of measurement results are difficult and measuring instruments used therein are poor in general versatility so that these methods are not widely accepted.